Manufacturing method for engine crankshaft for agricultural machine

The invention provides a manufacturing method for an engine crankshaft for an agricultural machine. The method comprises the following steps that the crankshaft is manufactured through non-quenching-tempering 50MnV alloy steel; smelting, refining, mold casting, rolling, forging and heat treatment are conducted; and in the heat treatment step, the forged crankshaft is heated to 650 DEG C, the temperature of 650 DEG C is kept for 15 min, then the temperature is increased to 850 DEG C for oil quenching, and after quenching at the temperature of 520 DEG C, cooling is conducted at the speed of 20-30 DEG C/ min. By the adoption of the manufacturing method for the engine crankshaft for the agricultural machine, it is provided by lots of experiments that through the non-quenching-tempering steel, by adopting the special heat treatment method, the strength of the crankshaft can be improved on the basis of guaranteeing the toughness of the non-quenching-tempering steel, and the manufacturing method is especially suitab